Project 2, Mechanisms of Neurobehavioral Dysfunction from Developmental Nicotine,& Tobacco, will determine how early life environmental tobacco smoke (ETS) exposure impacts neuronal differentiation, neural circuit formation and behavioral development resulting in persisting cognitive and emotional dysfunction. Neuronal and behavioral mechanisms will be studied in experiments tracing the progress from the incipient exposures to nicotine and tobacco during critical stages of cellular and organismal development, to the epigenetic and synaptic mechanisms that underiie behavioral dysfunction. Using a well characterized rat model for neurodevelopment, tobacco and nicotine will be administered by minipumps implanted subcutaneously to enable for continuous exposure that avoids the known stressors for rats that accompany direct smoke exposure. Cause and effect relationships between impacts on attention and memory as well as emotional function will be determined. We will compare the effects of tobacco and nicotine ranging from higher exposures modeling active maternal smoking to lower exposures characteristic of ETS. This project will provide the mechanistic link translating the epigenetic impacts of ETS to the cognitive impairments seen in children after developmental ETS exposure. Synaptic mechanisms underlying these behavioral effects will be determined with assessment of acetylcholine, dopamine, norepinephrine and serotonin systems known to be affected by nicotine exposures associated with active smoking during pregnancy. Cellular phenotypes of ETS and nicotine exposure will be determined in three validated in vitro models of neurodifferentiation, nerve growth factor-induced differentiation of rat PC12 ceils, differentiation of rat embryonic stem ceils to neurons and glia, and transdifferentiated human induced neurons. The investigation of epigenetic and neurochemical alterations from ETS will lead to studies of rescue and therapeutic treatments to avoid or reverse developmental ETS-induced cognitive and emotional dysfunction. This project will provide critical mechanistic translation between the molecular epigenetic studies of Project 3 and the clinical studies of ADHD in Project 1 to help children avoid lifelong impairment from developmental ETS exposure.